Method for automatically determining adjustments for stepping photolithography exposures

Abstract

A method and system for analyzing the stepping of a reticle mask. A reticle mask includes a first and second corner mask for blocking exposure of a first rectangular area on the wafer surface, a third corner mask for blocking exposure of a second rectangular area on the wafer surface, wherein the first rectangular area is larger than the second rectangular area, and a fourth corner mask of the reticle mask for allowing exposure of a third rectangular area that is smaller than the second rectangular area. A metrology machine produces alignment adjustment values of the result of stepping the reticle mask over the wafer's surface according to reticle mask overlapped exposed corners. The alignment adjustment values comprise an x and y value, and a rotation value. The alignment adjustment values are determined from the difference between the centers of the overlapping results of the third and fourth corner mask.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:  
     
       1. A stepping analysis method for analyzing the stepping of a reticle mask during exposures over the surface of a photoresist coated wafer, said method comprising: 
       generating a reticle mask comprising:  
       a first and second corner mask of the reticle mask for blocking exposure of a first rectangular area on the wafer surface;  
       a third corner mask of the reticle mask for blocking exposure of a second rectangular area on the wafer surface, wherein the first rectangular area is larger than the second rectangular area; and  
       a fourth corner mask of the reticle mask for allowing exposure of a third rectangular area that is smaller than the second rectangular area, wherein the first, second, third and fourth corner masks are configured to overlap in the stepping process;  
       using a metrology machine for producing alignment adjustment values of the result of stepping the reticle mask over the wafer's surface according to reticle mask overlapped exposed corners.  
     
     
       2. The method of claim  1 , wherein alignment adjustment values comprise the difference between the centers of the overlapping results of the third and fourth corner mask. 
     
     
       3. The method of claim  2 , wherein the alignment adjustment values are determined from an x and y value, and a rotation value. 
     
     
       4. A reticle mask for allowing stepping analysis based on exposed and developed results of a wafer's surface according to the reticle mask, said reticle mask comprising: 
       a first and second corner mask of the reticle mask for blocking exposure of a first rectangular area on the wafer surface;  
       a third corner mask of the reticle mask for blocking exposure of a second rectangular area on the wafer surface, wherein the first rectangular area is larger than the second rectangular area; and  
       a fourth corner mask of the reticle mask for allowing exposure of a third rectangular area that is smaller than the second rectangular area, wherein the first, second, third and fourth corner masks are configured to overlap in the stepping process.  
     
     
       5. A stepping analysis system for analyzing the stepping of a reticle mask during exposures over the surface of a photoresist coated wafer, said system comprising: 
       a reticle mask comprising:  
       a first and second corner mask of the reticle mask for blocking exposure of a first rectangular area on the wafer surface;  
       a third corner mask of the reticle mask for blocking exposure of a second rectangular area on the wafer surface, wherein the first rectangular area is larger than the second rectangular area; and  
       a fourth corner mask of the reticle mask for allowing exposure of a third rectangular area that is smaller than the second rectangular area, wherein the first, second, third and fourth corner masks are configured to overlap in the stepping process;  
       using a metrology machine for producing alignment adjustment values of the result of stepping the reticle mask over the wafer's surface according to reticle mask overlapped exposed corners.  
     
     
       6. The system of claim  5 , wherein the alignment adjustment values comprise an x and y value, and a rotation value. 
     
     
       7. The system of claim  6 , wherein alignment adjustment values are determined from the difference between the centers of the overlapping results of the third and fourth corner mask.